Now to the lightning rod issue we've been reporting on, the immigration debate. Key republicans coming on board with democrats. But american taxpayers may be spending a lot of money for that compromise. Tonight abc's jim avila takes us to the border. We asked for the numbers. How much are americans going to spend to make the politicians happy on this? Reporter: Here's reality at the border. America already spends $18 billion a year to stop illegal immigration like this. Most say it's working, 22 undocumented immigrants arrested in houston. Just yesterday. Caught by a record number of border patrol agents, using drones, cameras, and fences like the ones we visited in el paso this spring. More money spent along the border than is spent on all other law enforcement combined. But here's the rub. Today, the white house and the bipartisan authors of the senate immigration bill agreed to spend $30 billion more taxpayer dollars over the next ten years, money many who live along the border, say just isn't needed. To stop illegal immigration. Illegal immigrants? No. No, I can't say that I see them because of the new technology, the more hiring of border patrol agents. It's hard. Reporter: But in washington, the expensive compromise survives to secure republican votes. Adding an additional 350 miles of border fence, and doubling -- one for every 1,000 feet of the mexican frontier. A militarization of american's southern boundary now labelled the border surge. Jim avila, abc news, washington.

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